Variable displacement swash plate type compressor

ABSTRACT

A variable capacity swash plate compressor includes a thrust flange  40  fixed to a shaft  5  and rotating in unison with the shaft  5,  a swash plate  10  connected to the thrust flange  40  via a linkage  42  and rotating in unison with the thrust flange  40  according to rotation thereof, a hinge ball  9  slidably mounted on the shaft  5,  for limiting an angle of the swash plate  10  with respect to the shaft  5,  and a piston  7  connected to the swash plate  10  via shoes  11  relatively rotating on sliding surfaces  10   a   , 10   b  of the swash plate  10,  and performing linear reciprocating motion within a cylinder bore  6  according to rotation of the swash plate  10,  wherein the angle of inclination of the swash plate  10  changes according to a change in pressure in a crankcase  8  within which the swash plate  10  is received, to thereby change a length of stroke of the piston  7.  In this variable capacity swash plate compressor, the center O 1  of the hinge ball  9  is positioned toward a front side with respect to the center O 2  of a plate portion  10   c  of the swash plate  10.

[0001] This application is a U.S. National Phase Application under 35 USC 371 of International Application PCT/JP01/03927 filed May 11, 2001.

TECHNICAL FIELD

[0002] This invention relates to a variable capacity swash plate compressor which has its delivery quantity changed by variation of the stroke length of each piston occurring according to an angle of inclination of a swash plate.

BACKGROUND ART

[0003]FIG. 6 is a cross-sectional view of a shaft and components associated therewith of a conventional variable-capacity swash plate compressor.

[0004] The shaft 105 has a thrust flange 140 rigidly fixed thereto, and a swash plate 110 mounted thereon via a hinge ball 109.

[0005] The hinge ball 109 is mounted in a manner slidable along the shaft 105, and restricts the inclination of the swash plate 11 with respect to the shaft 105.

[0006] The thrust flange 140 and the swash plate 110 are connected by a linkage 142 via which the rotation of the shaft 105 is transmitted from the thrust flange 140 to the swash plate 110.

[0007] The piston 107 is connected to the swash plate 110 via a pair of shoes 111 relatively rotating on the sliding surfaces of the swash plate 110, and performs linear reciprocating motion within a cylinder bore (not shown) according to the rotation of the swash plate 110.

[0008] In the variable capacity swash plate compressor, in response to a change in pressure in a crankcase 108 accommodating the swash plate 110, the angle of inclination of the swash plate 110 is changed, whereby the stroke length of the piston 107 is changed.

[0009] The swash plate 110 is inclined about the center O1 of the hinge ball 109, and hence the position of the center of gravity O3 of the swash plate 110 is changed with respect to the shaft 105.

[0010]FIG. 7 is a diagram useful in explaining the static imbalance of a swash plate with respect to the angle of inclination of the swash plate.

[0011] Static imbalance occurs in a rotary member (swash plate 110 or thrust flange 140) rotating about the shaft 105. The amount of static imbalance is represented by the product (kg·cm) of a mass (kg) of the swash plate 110 (thrust flange 140) and the distance (cm) from the shaft 105 to the center of gravity of the swash plate 110 (thrust flange 140).

[0012] In FIG. 7, a, b, c, d, and e represent a static imbalance of the thrust flange, a static imbalance of the whole rotational assembly, a static imbalance occurring when the center of the hinge ball is positioned toward the front side with respect to the center of a plate portion of the swash plate, a static imbalance of the center of the hinge ball, and a static imbalance of the swash plate, respectively.

[0013] The angle of inclination of the thrust flange 140 is not varied, and hence the thrust flange has a fixed amount of static imbalance (see straight line e).

[0014] On the other hand, the angle of inclination of the swash plate 110 is changed, and hence the swash plate 110 has an amount of imbalance which varies at a fixed rate (see straight line b).

[0015] The sum of the amounts of static imbalance of the two members is the amount of the static imbalance of the whole rotational assembly (see straight line b).

[0016] When this amount of static imbalance increases, a rotation-related first-order vibration occurs in which the compressor itself vibrates, and it appears as a vibration of the vehicle and noise. This vibration provides a low-frequency noise in an audible range of 400 Hz or lower, and gives discomfort to the passengers.

[0017]FIG. 8 is a diagram useful for explaining the position of center of gravity of a swash plate.

[0018] In FIG. 8, A1, A2, B1, and B2 represent positions of center of gravity, Amax represents an amount of displacement of the position of center of gravity of the swash plate in the direction of the Y axis during the maximum stroke, Amin represents an amount of displacement of the swash plate in the direction of the Y axis during the minimum stroke, Bmax represents an amount of displacement of the position of center of gravity of the swash plate in the direction of the Y axis during the maximum stroke when a weight is added to the rear side, and Bmin represents an amount of displacement of the swash plate in the direction of the Y axis during the minimum stroke when the weight is added-to the rear side.

[0019] Recently, there has been an increasing demand on the smaller and faster compressor.

[0020] When the compressor is increased in its speed, the inertial force of the piston 107 increases with rotational speed of the compressor, and therefore, to strike a balance with the increasing inertial force, it is necessary to make the swash plate 110 thick or heavy.

[0021] In the variable capacity swash plate compressor, a weight (extra thickness) is added to the front side of the swash plate 110 to strike the balance with the inertial force. This weight increases as the compressor becomes faster.

[0022] However, when the added weight is increased, the weight of the front side of the swash plate 110 is increased, and at the same time, the distance from the center O1 of the hinge ball 109 to the center of gravity O3 of the swash plate 110 becomes longer, which degrades the static imbalance (increases the amount of static imbalance).

[0023] When the position of the center of gravity O3 of the swash plate 110 is changed with respect to the angle of inclination of the swash plate 110, resulting in an increased distance from the center O1 of the hinge ball 109 to the center of gravity O3 of the swash plate 110, the difference between the amount of static imbalance during the maximum stroke and that of static imbalance during the minimum stroke is increased to increase variation of static imbalance of the whole rotational assembly including the thrust flange 140 (see straight line b in FIG. 7).

[0024] Therefore, although the increased rotational speed of the compressor can be coped with by adding the weight to the front side of the swash plate 110, the rotation-related first-order vibration becomes large, which causes the vehicle to produce larger vibration and noise. Therefore, conventionally, a weight 112 is also added to the rear side of the swash plate 110 to thereby make the position of center of gravity of the swash plate 110 closer to the center O1 of the hinge ball (see FIG. 6).

[0025] This increases the mass of the swash plate 110, and to obtain the static imbalance of the whole compressor, the mass of the thrust flange 140 is also increased, which makes the compressor heavy in weight.

[0026] It is an object of the invention to provide a variable capacity swash plate compressor excellent in high-speed controllability which is capable of suppressing degradation of static imbalance without making a swash plate heavy in weight.

DISCLOSURE OF INVENTION

[0027] It is an object of the invention to provide a variable capacity swash plate compressor

[0028] To attain the above object, the present invention provides a variable capacity swash plate compressor including a rotational member fixed to a shaft and rotating in unison with the shaft, a swash rotational plate connected to the rotational member via a linkage and rotating in unison with the rotational member according to rotation thereof, an angle-limiting member slidably mounted on the shaft, for limiting an angle of the swash rotational plate with respect to the shaft, and a piston connected to the swash rotational plate via shoes relatively rotating on sliding surfaces of the swash rotational plate, and performing linear reciprocating motion within a cylinder bore according to rotation of the swash rotational plate, wherein the angle of inclination of the swash rotational plate changes according to a change in pressure in a crankcase within which the swash rotational plate is received, to thereby change a length of stroke of the piston, characterized in that a center of the angle-limiting member is positioned toward a front side with respect to a center of a plate portion of the swash rotational plate.

[0029] Since the center of the angle-limiting member is positioned toward the front side with respect to the center of the plate portion of the swash rotational plate, the center of the angle-limiting member is made closer to the center of gravity of the swash plate, whereby the distance from the center of the angle-limiting member to the center of gravity of the swash plate is reduced. Therefore, the center of the angle-limiting member becomes closer to the center of gravity of the swash rotational plate, which reduces the amount of static imbalance. Further, when the center of gravity of the swash plate is changed with respect to the angle of inclination of the swash plate, the difference between the amount of static imbalance during the maximum stroke and that of static imbalance during the minimum stroke is small, which reduces variation in the amount of static imbalance of the whole rotational assembly including the rotational member.

[0030] Preferably, the center of the angle-limiting member is made coincident with a center of gravity of the swash rotational plate.

[0031] Since the center of the angle-limiting member is made coincident with the center of gravity of the swash rotational plate, the amount of static imbalance is reduced to zero. Therefore, the mass of the rotational member can be reduced, whereby the weight of the compressor can be further reduced.

[0032] The present invention provides a variable capacity swash plate compressor including a rotational member fixed to a shaft and rotating in unison with the shaft, a swash rotational plate connected to the rotational member via a linkage and rotating in unison with the rotational member according to rotation thereof, a shaft insertion central hole formed through the swash rotational plate, and having the shaft extending therethrough, the shaft insertion central hole limiting an angle of the swash rotational plate with respect to the shaft, and a piston connected to the swash rotational plate via shoes relatively rotating on sliding surfaces of the swash rotational plate, and performing linear reciprocating motion within a cylinder bore according to rotation of the swash rotational plate, wherein the angle of inclination of the swash rotational plate changes according to a change in pressure in a crankcase within which the swash rotational plate is received, to thereby change a length of stroke of the piston, characterized in that a center of a circle formed by an edge line of the shaft insertion central hole is positioned toward a front side with respect to a center of a plate portion of the swash rotational plate.

[0033] Since the center of the circle formed by the edge line of the shaft insertion central hole is positioned toward the front side with respect to the center of the plate portion of the swash rotational plate, the center of the angle-limiting member is made closer to the center of gravity of the swash plate, whereby the distance from the center of the angle-limiting member to the center of gravity of the swash plate is reduced. Therefore, the center of the angle-limiting member becomes closer to the center of gravity of the swash rotational plate, which reduces the amount of static imbalance. Further, when the center of gravity of the swash plate is changed with respect to the angle of inclination of the swash plate, the difference between the amount of static imbalance during the maximum stroke and that of static imbalance during the minimum stroke is small, which reduces variation in the amount of static imbalance of the whole rotational assembly including the rotational member.

[0034] Preferably, the center of the circle formed by the edge line of the shaft insertion central hole is made coincident with a center of gravity of the swash rotational plate.

[0035] Since the center of the circle formed by the edge line of the shaft insertion central hole is made coincident with the center of gravity of the swash rotational plate, the amount of static imbalance is reduced to zero. Therefore, the mass of the rotational member can be reduced, whereby the weight of the compressor can be further reduced.

BRIEF DESCRIPTION OF DRAWINGS

[0036]FIG. 1 is a longitudinal cross-sectional view of a variable capacity swash plate compressor according to a first embodiment of the invention;

[0037]FIG. 2 is a diagram useful in explaining the position of center of gravity of a swash plate;

[0038]FIG. 3 is a diagram useful in explaining the position of center of gravity of a swash plate;

[0039]FIG. 4 is a longitudinal cross-sectional view of a variable capacity swash plate compressor according to a second embodiment of the invention;

[0040]FIG. 5 is a longitudinal cross-sectional view of a variable capacity swash plate compressor according to a third embodiment of the invention;

[0041]FIG. 6 is a cross-sectional view of a shaft and components associated therewith of a conventional variable capacity swash plate compressor;

[0042]FIG. 7 is a diagram useful in explaining the static imbalance with respect to the angle of inclination of a swash plate; and

[0043]FIG. 8 is a diagram useful in explaining the position of center of gravity of the swash plate.

BEST MODE FOR CARRYING OUT THE INVENTION

[0044] The invention will now be described in detail with reference to drawings showing preferred embodiments thereof.

[0045]FIG. 1 is a longitudinal cross-sectional view of a variable capacity swash plate compressor according to a first embodiment of the invention, and FIG. 2 is a diagram useful in explaining the position of center of gravity of a swash plate.

[0046] In FIG. 2, A1, A2, D1, and D2 represent positions of center of gravity, Amax represents an amount of displacement of the position of center of gravity of the swash plate 10 in the direction of the Y axis during the maximum stroke, Amin represents an amount of displacement of the swash plate 10 in the direction of the Y axis during the minimum stroke, Dmax represents an amount of displacement of the position of center of gravity of the swash plate 10 in the direction of the Y axis during the maximum stroke when the center O1 of a hinge ball 9 is positioned toward the front side with respect to the center O2 of a plate portion 10 c of the swash plate 10, and Dmin represents an amount of displacement of the swash plate 10 in the direction of the Y axis during the minimum stroke when the center O1 of the hinge ball 9 is positioned toward the front side with respect to the center O2 of the plate portion 10 c of the swash plate 10.

[0047] The variable capacity swash plate compressor has a cylinder block 1 having one end thereof secured to a rear head 3 via a valve plate 2 and the other end thereof secured to a front head 4.

[0048] The cylinder block 1 has a plurality of cylinder bores 6 axially extending therethrough at predetermined circumferential intervals about the shaft 5.

[0049] Each cylinder bore 6 has a piston 7 received therein.

[0050] A pair of shoes 11 are slidably supported at one end of the piston 7. The periphery of the swash plate 10 enters between the shoes 11, and respective flat portions of the shoes 11 are in contact with the sliding surfaces 10 a, 10 b of the swash plate 10.

[0051] The rotation of the swash plate 10 is converted to the linear reciprocating motion of each piston 7 via the shoes 11, and the piston 7 slides within the cylinder bore 6.

[0052] The front head 4 defines therein a crankcase 8 in which is received the swash plate (swash rotational plate) 10 which rotates about the hinge ball (angle-limiting member) 9 in a manner interlocked with rotation of the shaft 5.

[0053] The hinge ball 9 is slidably mounted on the shaft 5, and limits the angle of inclination of the swash plate 10 with respect to the shaft 5.

[0054] The center O1 of the hinge ball 9 is positioned toward the front side with respect to the center O2 of the plate portion 10 c of the swash plate 10. At this time, between Amax, Amin, Bmax, Bmin, Dmax, and Dmin, there is a relationship defined as (Amax−Amin)>(Bmax−Bmin)>(Dmax−Dmin) (see FIGS. 2 and 7).

[0055] Within the rear head 3, there are formed a discharge chamber 12, and a suction chamber located around the discharge chamber 12.

[0056] The valve plate 2 is formed with refrigerant outlet ports 16 each for communicating between a compression chamber 6 a of a cylinder bore 6 and the discharge chamber 12, and refrigerant inlet ports 15 each for communicating between a compression chamber 6 a of a cylinder bore 6 and the suction chamber 13. The refrigerant outlet ports 16 and the refrigerant inlet ports 15 are arranged at predetermined circumferential intervals.

[0057] The refrigerant outlet ports 16 are opened and closed by respective discharge valves 17. The discharge valves 17 are fixed to a rear head-side end face of the valve plate 2 by a bolt 19 together with a valve stopper 18.

[0058] Further, the refrigerant inlet ports 15 are opened and closed by respective suction valves 21 arranged between the valve plate 2 and the cylinder block 1.

[0059] The shaft 5 has a rear-side end thereof supported by a radial bearing 24 and a thrust bearing 25 and a front-side end thereof supported by a radial bearing 26.

[0060] Further, a pressure control valve 32 arranged in an intermediate portion of a communication passage 31 communicating between the discharge chamber 12 and the crankcase 8 controls pressure in the discharge chamber 12 and pressure in the crankcase 8.

[0061] The shaft 5 has a thrust flange (rotational member) 40 fixed thereto, and the swash plate 10 mounted thereon via the hinge ball 9. The hinge ball 9 is slidably fitted on the shaft 5.

[0062] The thrust flange 40 and the swash plate 10 are connected by a linkage 42, and rotation of the shaft 5 is transmitted from the thrust flange 40 to the swash plate 10 via the linkage 42.

[0063] A coil spring 51 is fitted between the hinge ball 9 and the thrust flange 40.

[0064] The coil spring 51 urges the hinge ball 9 toward the cylinder block side so as to decrease the angle of inclination of the swash plate 10.

[0065] Next, the operation of the variable capacity swash plate compressor constructed as above will be described.

[0066] As torque of an engine, not shown, installed on an automotive vehicle, not shown, is transmitted to the shaft 5 to rotate the same, the torque of the shaft 5 is transmitted to the thrust flange 40.

[0067] The swash plate 10 performs rotating motion about the hinge ball 9 in unison with the thrust flange 40 according to rotation of the thrust flange 40.

[0068] The rotating motion of the swash plate 10 is transmitted via the shoes 11 to the piston 7, and converted to linear reciprocating motion of the piston 7.

[0069] As a result, the volume of a compression chamber 6 a within the cylinder bore 6 changes, which causes suction, compression and delivery of refrigerant gas to be sequentially carried out, whereby the refrigerant gas is delivered in an amount corresponding to the angle of inclination of the swash plate 10.

[0070] During the suction, the corresponding suction valve 21 opens to draw low-pressure refrigerant gas from the suction chamber 13 into the compression chamber 6 a within the cylinder bore 6.

[0071] Further, during the delivery, the corresponding discharge valve 17 opens to deliver high-pressure refrigerant gas from the compression chamber 6 a to the discharge chamber 12.

[0072] When the pressure within the crankcase 8 increases due to a decrease in cooling load, the angle of inclination of the swash plate 10 decreases, which decreases the stroke length of the piston 7 to reduce the delivery quantity of the compressor.

[0073] When the pressure within the crankcase 8 decreases due to an increase in cooling load, the angle of inclination of the swash plate 10 increases.

[0074] As the angle of inclination of the swash plate 10 increases, the stroke length of the piston 7 is increased to increase the delivery quantity of the compressor.

[0075] According to the variable capacity swash plate compressor of this embodiment, the center O1 of the hinge ball 9 is close to the center of gravity O3 of the swash plate 10, and hence the amount of static imbalance becomes smaller, which makes it possible to suppress generation of vibrations and noise of the vehicle during high-speed rotation of the compressor without increasing the weight of the swash plate 10 (compressor), and adjust the amount of static imbalance more easily than by adding a weight to the rear side of the swash plate 10 to make the position of center of gravity of the same closer to the center of the hinge ball.

[0076] Further, since the relationship of (Amax−Amin)>(Bmax−Bmin)>(Dmax−Dmin) holds, the difference between the amount of static imbalance during the maximum stroke and that of static imbalance during the minimum stroke is reduced, which makes it possible to reduce the variation in the static imbalance of the whole rotational assembly including the thrust flange 40 (see straight line c in FIG. 7).

[0077]FIG. 3 is a diagram useful in explaining the center Of gravity of a swash plate.

[0078] This diagram shows a case in which when the center O1 of the hinge ball 9 is positioned toward the front side with respect to the center O2 of the plate portion 10 c of the swash plate 10, the center O1 of the hinge ball 9 is made coincident with the center of gravity O3 of the swash plate 10.

[0079] At this time, the amount of static imbalance is reduced to zero, the mass of the thrust flange 40 can be reduced, whereby the weight of the variable capacity swash plate compressor can be further reduced.

[0080] Although in the above embodiment, the invention is applied to a variable capacity swash plate compressor which uses the hinge ball 9, this is not limitative, but it may be applied to a variable capacity swash plate compressor which does not use the hinge ball 9.

[0081]FIG. 4 is a longitudinal cross-sectional view of a variable capacity swash plate compressor according to a second embodiment of the invention, and component parts identical to those of the first embodiment are designated by the same reference numerals and description thereof will be omitted.

[0082] This embodiment is distinguished from the first embodiment in that an angle-limiting member is formed by a slider 59 which is axially slidable on the shaft 5 and a pin 58 perpendicular to the axial direction of the slider 59.

[0083] The swash plate 60 is made variable in the angle of inclination thereof by the slider 59 and the pin 58, and a through hole 61 limits the angle of inclination of the swash plate 60 with respect to the shaft 5.

[0084] The center O1 of the slider 59 is positioned toward the front side with respect to the center O2 of a plate portion 60 a of the swash plate 60.

[0085] According to this embodiment, the same advantageous effects as provided by the first embodiment can be obtained.

[0086]FIG. 5 is a longitudinal cross-sectional view of a variable capacity swash plate compressor according to a third embodiment of the invention, and component parts identical to those of the first embodiment are designated by the same reference numerals and description thereof will be omitted.

[0087] This embodiment is distinguished from the first embodiment in that an angle-limiting member is formed by a shaft insertion central hole 81 formed through a swash plate 80.

[0088] The shaft insertion central hole 81 limits the angle of inclination of the swash plate 80 with respect to the shaft 5.

[0089] The shaft insertion central hole 81 is restricted in diameter at a center of the plate portion 80 a of the swash plate 80, and increased toward the front side and the rear side.

[0090] The center O1 of a circle formed by an edge line 81 a of the shaft insertion central hole 81 is positioned toward the front side with respect to the center O2 of the plate portion 80 a of the swash plate 80.

[0091] According to this embodiment, the same advantageous effects as provided by the first embodiment can be obtained.

[0092] Further, by making the center O1 of the circle formed by the edge line 81 a of the shaft insertion central hole 81 coincident with the center of gravity of the swash plate 80, the amount of static imbalance can be reduced to zero to thereby reduce the weight of the thrust flange 40, whereby the weight of the variable capacity swash plate compressor can be further reduced.

[0093] Although in the above embodiments, description is given, by way of example, on the variable capacity swash plate compressors in which the swash plates 10, 60, and 80 rotate in unison with the shaft 5, this is not limitative, but the invention can be applied to other compressors, such as a wobble plate compressor. In this case, the wobble plate corresponds to the swash rotational plate of the present invention.

INDUSTRIAL APPLICABILITY

[0094] As described above, the variable capacity swash plate compressor according to the invention is useful as a refrigerant compressor for an air conditioner installed on a vehicle, such as a passenger car, a bus or a truck, and particularly suitable for an air conditioner which controls the delivery quantity of refrigerant gas according to the demanded degree of cooling capacity. 

1. A variable capacity swash plate compressor including: a rotational member fixed to a shaft and rotating in unison with the shaft, a swash rotational plate connected to said rotational member via a linkage and rotating in unison with said rotational member according to rotation thereof, an angle-limiting member slidably mounted on the shaft, for limiting an angle of said swash rotational plate with respect to the shaft, and a piston connected to said swash rotational plate via shoes relatively rotating on sliding surfaces of said swash rotational plate, and performing linear reciprocating motion within a cylinder bore according to rotation of said swash rotational plate, wherein the angle of inclination of said swash rotational plate changes according to a change in pressure in a crankcase within which said swash rotational plate is received, to thereby change a length of stroke of said piston, characterized in that: a center of said angle-limiting member is positioned toward a front side with respect to a center of a plate portion of said swash rotational plate.
 2. A variable capacity swash plate compressor according to claim 1, wherein the center of said angle-limiting member is made coincident with a center of gravity of said swash rotational plate.
 3. A variable capacity swash plate compressor including: a rotational member fixed to a shaft and rotating in unison with the shaft, a swash rotational plate connected to said rotational member via a linkage and rotating in unison with said rotational member according to rotation thereof, a shaft insertion central hole formed through said swash rotational plate, and having said shaft extending therethrough, said shaft insertion central hole limiting an angle of said swash rotational plate with respect to the shaft, and a piston connected to said swash rotational plate via shoes relatively rotating on sliding surfaces of said swash rotational plate, and performing linear reciprocating motion within a cylinder bore according to rotation of said swash rotational plate, wherein the angle of inclination of said swash rotational plate changes according to a change in pressure in a crankcase within which said swash rotational plate is received, to thereby change a length of stroke of said piston, characterized in that: a center of a circle formed by an edge line of said shaft insertion central hole is positioned toward a front side with respect to a center of a plate portion of said swash rotational plate.
 4. A variable capacity swash plate compressor according to claim 3, wherein the center of the circle formed by the edge line of said shaft insertion central hole is made coincident with a center of gravity of said swash rotational plate. 